Instance Command Execution

[Hye-Dev]

Allow for executing custom commands on instances using POST /1.0/instances/{name}/exec

Interactive should always be true. Keep the other keys (other than the command to execute) default.

1. Add a button for command execution on the console page. The InstanceExec should be a component defined via deps/ararat-ui-web (make a PR to that submodule as well), and use similar context to that of the console. Add additional functions to the same class file as needed.
2. When this button is pressed, it should open a dialog. The dialog should ask for the command to execute.
3. Once the command is submitted, the dialog will show an interactive Xterm (similar to how the console works)

If any logic between the existing text console component and this new InstanceExec component are shared, share them. We don't want duplicate logic.